Conventional image forming devices have a scanner function that converts a medium, such as paper, into image data and a printing function that prints the image data. Further, such image forming devices have an image display that displays image data and an image editor for correcting a position of image data, in order to overlap and align two image data.
When both sides of a manuscript are printed, the image forming device performs a process to reverse the image data on the back side (reverse horizontal or reverse vertical); next, performs a process to synthesize the reversed image data on the back side and the image data on the front side; and further performs a process to display the synthesized image data on the image display. Then, while browsing the synthesized image displayed on the image display, a user manually moves the image data of the back side, which was reversed by the image edit means, and to adjust the position of the image data to align a medium region contained in the reversed image data on the back side with a medium region contained in the image data on the front side. With this manual operation, the image forming device can print both sides where the image data are aligned. See JP Laid-Open Publication No. 2003-244420.